Finnish researchers used validated survey data to assess factors affecting productivity, as well as perceived health and quality of life among a random sample of 5000 adults aged between 30 and 64.
All the participants had already taken part in the national Health 2000 survey.
Of the 3536 people who worked full time, around 90% completed the questionnaires designed to measure perceived productivity, health status, and quality of life.
Of those working full time, almost 10% were self-employed entrepreneurs of whom 3.5% were farmers.
The farmers and entrepreneurs tended to be older than the salaried workers, and all the self employed who were sole traders tended to have lower levels of educational attainment and incomes than their peers with staff and salaried workers.
Self employed entrepreneurs with staff scored the highest on all the measures assessed. Farmers scored the lowest.
When productivity was assessed separately, more than a third of farmers achieved low or average scores. This compares with 16% of salaried workers and sole traders and 12% of entrepreneurs with staff.
After taking account of a range of influential factors, such as age, long term conditions, and loving relationships, entrepreneurs with staff and salaried workers scored around the same.
But farmers still fared the worst.
Previous research has suggested that the jobs which are best for health and wellbeing are those in which the worker has a good deal of control and support, irrespective of the demands made on him/her.
Self employed people tend to have more control over their working lives, but their work tends to be more stressful, say the authors, who conclude that farmers in particular need more social and emotional support.